Throughout the specification, including the claims, the expressions “earth” and “earth formation” are used in a broad sense to denote any nonhomogeneous, dispersive medium having complex permittivity. Important examples of such media include subterranean formations such as soil, hardpan, and bedrock and bodies of water (such as the ocean) above such subterranean formations.
Two types of pulse transformers are mentioned in this specification: “transmission line” and “conventional”. The important parameters that are utilized for frequency control of radiation involve the magnetic cores and the magnetic inductance resulting from conductor turns on the core. In an equivalent electric circuit this gives rise to “magnetic flux currents” as an identifying term for such transformers.
In the prior art pertaining to this invention, U.S. Pat. No. 5,192,952, issued March 1993, and U.S. Pat. No. 5,280,284, issued January 1994 a method and apparatus of sending signals into the earth and a method of processing such signals to describe the electrical properties of the earth as a function of depth in the earth is presented.
At the present juncture in the development of the science demonstrated in these patents it is appropriate to expand the methods and and apparatus for operation aloft in an aircraft. This leads to the use of lower frequencies and a concomittant greater depth of penetration into the earth. Such expansion improves the usefulness and economic value of the capacitor concept.
In this connection, attention is drawn to prior art discussion of the radiation, induction and electrostatic field of an electrical point source discussed by Johler et al in NBS Circular 573 “Phase of the low-radio frequency ground wave”. In this document a multiplying factor of the radiation fields was isolated from a solution of Maxwell's Equations for an electrical point source in the form of a dipole and numerical computations were made showing the effects of such radiation fields at various low frequencies. (1000–20 KHz). The multiplying factor, FI, was isolated as multiplied by the radiation field E, which at great distance in wavelengths from the point source reduced to unity giving a pure radiation field, EFI=TOTALP−FIELD. Thus,
      F    r    =            1      +              1        iKz            +              1                              (            iKz            )                    2                      →    1  as the dipole equatorial distance, z gets large in wavelengths, FI approaches 1. Here K is the wave number of the medium and i=√−1. The second and third terms produce effects due to the radiation apparatus, in this case an electrical point source. A complete derivation of the electrical point source is given by J. A. Straton (1941)p435, eqs. 25&26. Of course for the case of a finite size source as shown in FIG. 1,2,3, the factor FI is much more complicated but this apparatus non-the-less exhibits an analogous behavior.
In the prior art the definition of real effective values of the electrical properties and their relation to physical theory of electromagnetic propagation in such media as the earth has been set forth in standard textbooks such as King et al (1981).